Industrial furnace



May Z0, 947. F, H I OFTUS 2,420,962

INDUSTRIAL FURNACE Filed sept. 8, 1945 2 sheets-sheet 1 JNVENTOR. Hm).Lorus Patented May 20, 1947 Unire sa amsn Tgs emessi* otros 13 Claims.

My invention relates to industrial furnaces, and is particularlydirected to certain new and useful improvements in furnaces for heatingelongate blanks or work pieces of aluminum, preparatory to a forging orrolling operation. The invention will be described as it has beendeveloped for such particular eld of service, with the understandingthat within the terms of the appended claims various other fields arewithin the contemplation of the invention.

In the accompanying drawings Fig. I is a fragf mentary view of a furnaceinstallation in which the invention has in exemplary way been embodied,and Fig. II is a View of the installation in transverse verticalsection. Fig. I appears partly in plan and partly in horizontal sectionon the plane I-I of Fig. II, while Fig. II, drawn to larger scale, showsthe furnace in vertical transverse section, on the plan II-II of Fig. I.

Referring to the drawings, the furnace installation in which theinvention is herein illustrated comprises a pit furnace having sidewalls 2, 2, end wall 3, 3, and a floor 4 constructed of refractorymasonry, externally sheathedin steel plate 5 and reinforced and tied bymeans of steel buckstays 6 that are anchored at their lower ends to aconcrete foundation 1. The pit 8 is closed from above by means of acover 9 adapted to swing on an axis IIJ between open and closedpositions, and in closed position the cover cooperates with apit-encompassing seal I I, to provide a substantially air-tight chamberin which the material to be heated or heat treated i-s enclosed. Thecover is power operated, but the means to this end, as well as thespecific details of the cover-sealing structure, are not an immediateconcern of my present invention, and for this reason will not bedescribed in detail.

Inlet ports I2 are provided in opposite walls of the furnaces forintroducing hot gases or burning columns of fuel into the chamber or pit8, and it will be noted that such inlet ports are located adjacent tothe top or cover of the chamber. In this case the inlet ports I 2 areprovided in the opposite side walls 2, 2; the ports are spaced apartlongitudinally of such side walls, as appears in Fig. I; and the fuel ispreferably, though not necessarily, burned at a point remote from theports, rather than being admitted immediately to the furnace chamber bymean-s of burners located in the ports.

More particularly, the fuel is burned in a combustion chamber I3 removedfrom the furnace structure proper, and the hot products of combustionare propelled by means of a fan 22 (driven by an electric motor 23)through a passage 24 into a flue I4 equipped with a damper I5. The ue I4is the inlet flue of the furnace. It comprises a tunnel flue thatextends longitudinally beneath the chamber or pit 8 of the furnace, andfrom such tunnel flue passageways I6 lead through the furnace hearth andside walls to the inlet ports severally. The passageways I6 are providedwith dampers Ilia which afford control of the hot gases flowing into thefurnace chamber. The hot products of combustion delivered into thefurnace chamber, at uniformly distributed points longitudinally thereof,sweep over and between the pieces of work to be heated- 'in this casebars B of aluminum--and nd escape in outgo ports I1.

The outgo ports I'I are formed in the iloor 4 of the furnace chamber,and are spaced apart on the longitudinal center-line thereof. An 'outlettunnel flue I 9 extends longitudinally beneath the furnace chamber, andto this flue the outgo ports deliver the exhaust gases by way ofpassageways E8. The tunnel flue I9 extends from the furnace to a pointadjacent to the remotely situated combustion chamber I3, and a duct 20affords communication between ue I9 and the ycombustion chamber. Aburner 2I is arranged to direct ud `fuel and air into the combustionchamber, and

under the propulsion offan 22, a continuous circulation of hot gases isestablished .and maintained. The hot gases generated by the combustionof fuel are delivered into the tunnel flue I4, whence they stream to andthrough the passageways I6 and ports I2 into the furnace chambercontaining the work to be heated.

As will present-ly appear in greater detail, the billets or bars B ofaluminum that constitute the furnace charge are positioned in a cradle25 of skeleton construction, and the individual bar-s are supported inspaced relation. The hot gases streaming into the top of the furnacechamber passl downward through the spaces between the bars B of thecharge and enter the outgo ports Il, whence they iiow through Athe outgoflue I9 and return to the combustion chamber I3. The hot gases owingthrough the furnace chamber yield large quantities of heat to the'furnace charge, and upon returning to the combustion chamber I3 theheat thus yielded by the ga-ses is restored by the burning fuel. In thisway, the residual heat Ain the gases leaving the work-heating chamber 8of the furnace is conserved, and the thermal efficiency of theinstallation maintained at maximum value. A quantity ofy gas is bledfrom the continuously circulating stream,

and such quantity is equal to the quantity of hot gases generated by thecombustion of fuel injected by the burner 2l. A vent 25 including avalve 2l is provided at the cool end of the combustion chamber, the endinto which the gases returning from the furnace enter the combustionchamber, and this vent provides for the bleeding away of the excess gas.The adjustment of the valves I5 and 28 in the flues I4 and I9,respectively, together with the adjustment of the bleeder valve 2l, andthe regulation of the speed of the fan and the rate of combustion withinthe chamber I3, affords the desired control of the circulating hotgases, and ofthe heatingeffect of the furnace. The adjustment of thedampers I 6a, that individually control the flow of the hot gases to theinlet ports I2, provides for the regulation of the heating effectlongitudinally of the furnace chamber. Uniform heating conditionsythroughout the extent of the furnace chamber are lobtained.

Having described furnace structure per se, at-` 'tention will 'now bedirected to the improved support for the work to be heated. A problem in`the heating of a batch of articles, such as the bars B, lhas been toprovide a uniform flow of the 'hot gases over the surfaces of all of thearticles; that is, a now of gases that Will afford uniform heatingeffect throughout all of the furnace charge. The cradle 25 affords asolution `of this problem.

A As already mentioned the rcradle 25 is of skeleton "construction, Moreparticularly, lthe 'cradle is formed lof a plurality of W shaped framemembers '(Fig. II) to which the reference numeral 25 is immediatelyapplied. These frame members arelspaced apart to provide an elongatecradle for the bars to be supported, and are integrated by -means ofsections 29 of I-beams extending in parallelism 'between the successivermembers l2li and being Welded thereto at the bottomsof the two Vs oftheW. The members 25 are vfurther united and reinforced by means of'longitudinal tie-rods 3i) extending Ybetween the side arms of saidvW-shaped framefmembers, as may cbe understood upon comparing Figs. Iand QII. The bodies or'limbs of the `W -shaped members 2 5 areof I-shapeVin cross section, and are provided-at Ithe upper ends of the limbs witheyes 31, whereby the 'cradle maybe engaged by a crane vand 'lifted withits load of Work pieces B into "and from the furnace chamber. The cradleVstructurels formed of cast iron or steel, a material of adequatestrength under the effect of the heat to which the aluminum bars B aresub- 'jected 'In-this case, the bars B are of a length `thatapproximately equals the length of the Yfurnace chamber, Aand thebar-supporting cradle is of commensurate length. In Fig. I the bars andthe cradle are shown fragmentarily, in orderthat the larrangement oftheoutgo ports Il inthe floor cradle, together With the spaced arrangementof the billets or bars B supported therein, provides for an uniformlydistributed flow of the hot gases through the group of supported bars.The spaces between the bars serve in effect as lues through which thehot gases, delivered by the ports I2, stream on their way to the outgoports I'I. The W-like arrangement of the group of bars is instrumentalin establishing a uniform pressure drop through all of the devious pathsof flow of the -hot gases, whereby substantially the same quantity ofhot gases flows through each of the paths, with the consequence that theheating ef- -fect Yis uniformly distributed to all of the bars in thecradle.

In addition to the described arrangement of the group `of bars to beheated, another important feature Vis to be noted. The sections 29 ofI-beam, that interconnect the frame members 25 of the cradle, form, Whenthe cradle is in position of service yupon lthe :hearth of the fur-nace,parallel ycurtain Walls that extend longitudinally of and on oppositesides of the line o'foutg-o ports 1'1. These curtain `walls prevent Aashort-circuit flow of the hot gases beneath the charge of bars 1B to theoutgo ports. See the arrows in Fig. 1'I that indicate the flow of thegases.

'Still another feature merits particular consideration. lt wiil beobserved that the central portions of each W-shaped frame member l25,that is, the portions that form the linverted V ofthe W, support thework in such position that Va longitudinally extending flue is providedabove the outgo ports Il. That Iis to say, the inverted V portions ofthe W-shaped frame members `25 are centered with `res-peet to the llineof outgo ports, and form with the :bod-ies of the supported 4bars B aflue into which the -gases streaming through nthe spaces between thebars-passontheir way into the outgo ports I1. The pro-vision of suchflue, particularly in conjunction with the curtain walls "2S,contributes to the realization of thedesireddistribution ofgaseousnovi/through the body ofthe furnace charge.

It-will be understood that various modifications Vof Vthe structuredescribed may be adopted 'with- `tending from said vflue to said `ports,a rsecond tunnel flue ext-ending parallel tothe rst tunnel flue underthe furnace chamber `and `communicating Withan outlet forwaste gases,outgo ports opening 'from the lsa-id'c'hamber at spaced-apart points,and passageways forwas-te gases leading from said foutgo ports to saidsecond tunnel flue.

2. A furnace including a Work-containing chamber, a tunnel 7flueextending-under the Ifurnace chamber, nfiea-ns forsuppl-yinghot gases to`such flue, inlet portsopeningth'rough the opposite side walls of thechamber at spaced-'apart points in the longitudinal extent-of suchwalls,

-passageways extending from said flue 'to said ports, a second tunnelflue extending parallel to the rst tuunel flue under the furnace"chamber and communicating with an outlet for waste gases, outgo vportsopening in the floor of the Vfurnace vchamber 'at Vspacedapart points`in 'the horizontal extent thereof Iand passageways for waste gases'extending from said outgo ports to said second tunnel flue.

3. A furnace including a work-containing chamber, a tunnel flueextending under the furnace chamber, means for supplying hot gases tosuch flue, inlet ports opening through the opposite side walls of thefurnace chamber at spaced-apart p-oints in the longitudinal extent ofsuch wall and adjacent to the top of said furnace chamber, passagewaysextending downward in the furnace structure and establishingcommunication between said ports and said tunnel iiue, a second tunnelflue extending parallel to the first tunnel flue under the furnacechamber and communicating with an outlet for waste gases, outgo portsopening through said floor at spaced-apart points in a longitudinalextent thereof, and passageways for waste gases leading from said outgoports to said second tunnel flue.

4. Apit furnace including a work-containing pit, a tunnel flue extendingunder the pit, means for supplying hot gases to said flue, inlet portsopening through the opposite side walls of the pit, said inlet portsbeing located adjacent to the top of the pit and being spaced apart inthe longitudinal extent of said side Walls, a second tunnel flueextending under said pit, outgo ports opening through the floor of saidpit below said ports and at spaced-apart points in the horizontal extentthereof, and passageways for Waste gases leading from said outgo portsto said second tunnel flue.

5. A pit furnace including a work-containing pit, a tunnel flueextending under the pit, means for supplying hot gases to said flue,inlet ports opening through the opposite side walls of the pit, saidinlet ports being located adjacent to the top of the pit and beingspaced apart in the longitudinal extent of said side walls, a secondtunnel flue extending under said pit, outgo ports opening through thefloor of said pit below said ports and at spaced-apart points inthehorizontal extent thereof, and passageways for waste gases leading fromsaid outgo ports to said second tunnel flue, means in said pit forsupporting a plurality of pieces of work in spaced-apart relationathwart the paths of flow of hot gases streaming from said inlet portsto said outgo ports.

6. A pit furnace including a work-containing pit, a tunnel iiueextending under the pit, means for supplying hot gases to said iiue,inlet ports opening through the opposite side walls of the pit, saidinlet ports being located adjacent to the top of the pit and beingspaced apart in the longitudinal extent of said side walls, a secondtunnel iiue extending under said pit,outgo ports opening through floorof said pit at spaced-apart points in the horizontal extent thereof, andpassageways for waste gases leading from said outgo ports to said secondtunnel flue, means in said pit for supporting a`plurality of pieces ofwork in spaced-apart relation athwart the paths of flow of hotgasesstreaming from said inlet ports to said outgo ports, said lastmeans comprising a cradle of skeleton construction and of W shape incross section. A

7. A pit furnace including` a work-containing pit, atunnel iiueextending under the pit, means for supplying hot gases to said ue, inletports opening through the opposite side walls of the pit, said inletports being located adjacent to the top of the pit and being spacedapart in the longitudinal extent of said side walls, a second tunneliiue extending under said pit and comgases into said chamber, an outgop-ort opening through the iloor of said chamber for leading waste gasestherefrom, anda cradle of skeleton construction for the support of aplurality of pieces of work in said chamber, said cradle being ofW-shape in cross section, with the inverted V of the W positioned oversaid outgo port.

9. A furnace including a work-containing chamber, inlet ports forintroducing hot gases through the opposite side walls of said chamber atspaced-apart points in the longitudinal extent thereof, outgoportsopening through the floor .of

the chamber at spaced-apart points in the extent of the center-linethereof, and a cradle of skeleton construction and W shape in crosssection for supporting a plurality of pieces of work in said chamber,said cradle being arranged with the inverted V of the W centered 'withrespect to said center-line.

10. A furnace includingV a work-containing chamber, inlet ports forintroducing hot gases through the opposite side walls of said chamber atspaced-apart points in the longitudinal extent thereof, outgo portsopening through the fico-r of the chamber at spaced-apart points on thecenter-line thereof, and a cradle of skeleton construction forsupporting a multiplicity of pieces of work in spaced-apart relation insaid chamber, said cradle being formed of material of higher resistanceto heat than the pieces of work contained therein, said cradle beingformed to provide in conjunction with the supported pieces of work aflue above the outgo ports in the fio-or of said pit.

11. A furnace including ,a work-containing chamber, inlet and outletflues extending under the furnace chamber, a plurality of inlet portsopening thro-ugh a wall of the furnace chamber at spaced-apart points inthe extent thereof, passageways extending from said inlet flue to saidinlet ports, a combustion chamber connected to deliver hot products ofcombustion into the inlet flue, a plurality of outgo ports opening fromthe furnace chamber, passageways c-onnecting said outgo ports to saidoutlet ilue, a passage from said outlet flue to said combustion chamber,means for supplying fuel to said combustion chamber, means forpropelling pro-ducts of combustion from said combustion chamber throughsaid inlet ue to said inlet ports and into the furnace chamber, fromsaid furnace chamber through said outgo ports into said outlet ue, andfrom the outlet flue back into said combustion chamber, and means forbleeding spent gases from such circulating stream of gases.

12. `A furnace including a work-containing chamber having a line ofoutgo ports opening through the floor of the chamber for the escape ofexhaust gases, means for supplying work-conditioning gases to saidchamber, a work-support of skeleton construction for supporting aplurality of pieces of work in said chamber, said work-support includingportions which, with the 7 work-support in service position Within thefurnace chamber, form baffles that extend longitudinally of and onopposite sides of said line of outgo ports, to provide within the loadedwork-support, the effect of a iue extending along said line of outgoports.

13. A furnace including a furnace chamber, means including inlet portsfor introducing hot gases to said chamber, outgo ports for leading gasesaway from the chamber, and means for supporting a group of elongatearticles spaced apart and extending horizontally across the lines offlow of the hot gases streaming from said iniet ports to said outgoports, said means being constructed to support said spaced-apartarticles, with the cross-sectional extent of the group decreased towardthe bottom of the group, whereby CES CITED The following references areof record in the le of this patent:

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